1. Field of the Invention
The present invention relates to a method of manufacturing pipes having sections with different wall thicknesses from an initially plane sheet metal.
2. Description of the Related Art
German Patent 33 43 709 A1 discloses a method of forming frame components of motor vehicles in which a sheet metal is initially rolled in such a way that parallel indentations are formed. These different wall thicknesses are to result from rolling the sheet metal by means of a roll having sections with different size diameters.
The rolled sheet metal is subsequently cut to size and the individual pieces are bent in longitudinal direction. In this manner, it is possible to produce frame components which have different wall thicknesses in cross-section, while having in longitudinal direction always a constant cross-section. It is not possible to produce areas with partially reduced wall thicknesses in longitudinal direction of the frame components in order to take into consideration peak stresses to be expected locally. The present invention starts at this point.